Frequent Feeding Reduces Group-Housed Horses' Aggression

Van Dierendonck's study showed that increased forage feeding frequency for group-housed horses could lead to a healthy balance between feeding and resting, even for lower ranked horses, and had no negative side effects.

Photo: prof. dr. Machteld van Dierendonck

Picture a large covered paddock housing dozens of horses. A machine moves in periodically to deposit feed, and a robot maneuvers around horse hooves to suck up manure. No, this isn't equine science fiction, it's a scene from a group housing study conducted by Dutch researchers.

Scientists like prof. dr. Machteld van Dierendonck, owner of Equus Research and Therapy in The Netherlands and honorary professor of equine behavior and welfare at Ghent University's Faculty of Veterinary Medicine, in Belgium, contend that group housing and feeding—if designed and introduced properly—is best for horses' mental and physical health. But housing large groups of horses loose together comes with its own set of risks and challenges.

So van Dierendonck and colleagues set out to determine whether an automatic feeding system with multiple feeding frequencies would improve horses' welfare in a well-integrated group of riding school ponies and horses. She presented their preliminary (not yet peer-reviewed) results at the 9th Annual International Society for Equitation Science, held July 18-20 at the University of Delaware, in Newark.

"Group housing sometimes has an increased risk of both insufficient feeding (e.g., less access to food or access to lower-quality food) and decreased resting time for lower-ranked horses and a higher chance of interaction-induced injuries (especially at feeding time)," van Dierendonck explained. To combat these risks, she proposed increasing group-housed horses' feeding frequency.

An automatic mucking machine shoveled manure 16 hours per day into a covered collection gutter in van Dierendonck's study.

Photo Courtesy prof. dr. Machteld van Dierendonck

In her study, van Dierendonck observed 47 riding school ponies and horses of all sizes, genders, and ages (with the exception of adult stallions) at their home location (as a control) and again after they relocated to a covered, 48-by-25-meter (157 by 82 feet) group-housing facility in April 2013.

This facility featured:

A large automatic feeding system, which sounded an alarm before distributing forage into long feeding troughs;

An automatic mucking machine that shoveled manure 16 hours a day into a covered collection gutter;

A 25-by-10-meter (82 by 33 feet) space bedded with straw to provide a place for horses to rest freely; and

Structures horses could "escape" behind to ensure tranquility in the resting area.

During the first, eight-day observation period at this new facility, the feeding system distributed forage three times a day—the amount of feedings the horses received at their previous location. During the second, 10-day observation period the system distributed forage six times a day. Van Dierendonck and coworkers hypothesized that with six feedings the horses would show less and milder aggression; they would have a more natural time budget (the time spent engaging in different behaviors during a day); low-ranking horses would have enough time to eat and rest; and social relationships and injury rate would remain unchanged.

Van Dierendonck used 24-hour video surveillance and about nine hours of direct observation daily to measure horses' aggression (e.g., threatening, biting, kicking, attacking, chasing) frequency, time budget, spatial relationships, and avoidance behavior. She then compared her observations during the three-feeding-a-day period to the six-feeding-a-day period. Before, during, and after these periods the team also assessed body condition scores (BCS) and performed health checks.

Upon reviewing their results the team determined that:

Average head threat frequency and overall aggression during the 10 minutes before feeding time decreased significantly with six feedings compared to three.

The anticipation upon hearing the alarm that forage was coming did not result in increased activity or aggression, as is usually the case with stalled horses. Van Dierendonck said this finding supports the husbandry theory (Spruijt et al.) that animals in suboptimal housing situations show signs of anticipation when they hear an announcement for something positive; animals in optimal situations show only moderate anticipation.

Aggression during the nonfeeding periods throughout the day was relatively low and did not differ between feeding schedules.

Horses spent more time resting and less time feeding with six feedings compared to three. "This was unexpected," van Dierendonck said, "but it is comparable to feral horses in the summer in a moderate climate."

Average body condition remained the same during both trials. "So despite the fact that all horses spent less time eating (with six feedings), their BCS stayed the same—even for the low-ranked horses," van Dierendonck said.

In conclusion, she said the researchers interpreted the results to indicate that increased forage feeding frequency for group-housed horses could lead to a healthy balance between feeding and resting, even for lower ranked horses, and had no negative side effects.

"Increasing feeding frequency gave the horses more control over their environment and thus improved their welfare," van Dierendonck said.

These results suggest it is worth studying whether increased forage feeding frequency could also benefit individually stabled horses and their feed anticipation levels.

About the Author

Alexandra Beckstett, Managing Editor of The Horse and a native of Houston, Texas, is a lifelong horse owner who has shown successfully on the national hunter/jumper circuit and dabbled in hunter breeding. After graduating from Duke University, she joined Blood-Horse Publications as Assistant Editor of its book division, Eclipse Press, before joining The Horse.

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